/Engine/Source/Runtime/Slate/Public/Framework/Application/SlateUser.h
Returns the cause for which the provided widget was focused, or nothing if the given widget is not the current focus target.
[TOptional](API\Runtime\Core\IO\TOptional)< EFocusCause > HasFocus ( [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< const [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > Widget ) const